Asi1600 or 8300ccd

[Allinthehead]

On 29/11/2018 at 11:01, DaveS said:

I have been using the ASI1600 as well as the SX 694, and prefer the SX. The amp-glow on the ASI does calibrate out fairly easily, but I had the devil's own time trying to calibrate it out of the ASI 183.

My next camera is likely to be a 16200 CCD, as I think CMOS isn't there yet unless you go to stupidly and ruinously expensive professional types, e.g. FLI Merlin 4040.

I would like to respectfully disagree?

[RayD]

9 minutes ago, Allinthehead said:

I would like to respectfully disagree?

Nice.........But 1,733 subs and over 55GB of data for one image.............

[david_taurus83]

5 minutes ago, RayD said:

Nice.........But 1,733 subs and over 55GB of data for one image.............

You mis counted the 30s Lum!!!!?

[Allinthehead]

5 minutes ago, RayD said:

Nice.........But 1,733 subs and over 55GB of data for one image.............

I know. He said it took 12 hrs to stack?

He could have lowered the gain and increased the sub length to reduce the pain. 

[RayD]

2 minutes ago, david_taurus83 said:

You mis counted the 30s Lum!!!!?

Crikey!!!!!  You're right.  That's 3724 subs and 119GB of data!

That's some serious processing power needed to stack that lot.  In reality I think it is pushing the limits of CMOS, and where you really need to use CCD.

[RayD]

1 minute ago, Allinthehead said:

I know. He said it took 12 hrs to stack?

He could have lowered the gain and increased the sub length to reduce the pain. 

I'm having a bash with CMOS having just bought a Horizon, but I won't be going to these extremes I have to say.

He's a patient man so full kudos ?

[tooth_dr]

The money you save on buying a CMOS is offset by the cost of buying a new high spec computer. 

[vlaiv]

1 minute ago, RayD said:

Crikey!!!!!  You're right.  That's 3724 subs and 119GB of data!

That's some serious processing power needed to stack that lot.  In reality I think it is pushing the limits of CMOS, and where you really need to use CCD.

Au contraire! He just showed that you don't really need to use one

 

[RayD]

1 minute ago, tooth_dr said:

The money you save on buying a CMOS is offset by the cost of buying a new high spec computer. 

And then some I would have thought!  I have a pretty hefty PC in my obsy, and I process on a very good 5K Mac, but I think both would struggle with this!!

[Allinthehead]

Just now, RayD said:

I'm having a bash with CMOS having just bought a Horizon, but I won't be going to these extremes I have to say.

He's a patient man so full kudos ?

He sure is. I tried the 30 and 60 second route for while but i soon tired of it. The waste of imaging time was the biggest problem, dithering between subs and the few seconds of download time for each image adds up over an entire run.

[RayD]

1 minute ago, vlaiv said:

Au contraire! He just showed that you don't really need to use one

 

On the contrary, I think he demonstrated very well that you do as this is a simply ridiculous number of subs and required processing power.

[david_taurus83]

Surely must have been calibrating and processing 1 filter while he was capturing the rest! Can you imagine how long it would take Pixinsight to stack that lot!!!

[Allinthehead]

3 minutes ago, RayD said:

I'm having a bash with CMOS having just bought a Horizon

Good luck with that by the way.

[RayD]

Just now, Allinthehead said:

He sure is. I tried the 30 and 60 second route for while but i soon tired of it. The waste of imaging time was the biggest problem, dithering between subs and the few seconds of download time for each image adds up over an entire run.

Yes indeed, Richard.  I'm not surprised. 

[RayD]

2 minutes ago, Allinthehead said:

Good luck with that by the way.

Cheers.  I'm looking forward to possibly doing a side-by-side capture with this and one of my CCD's (dual Esprit 100's) and making the data available for everyone to have a look and a play.

[Allinthehead]

Just now, RayD said:

Cheers.  I'm looking forward to possibly doing a side-by-side capture with this and one of my CCD's (dual Esprit 100's) and making the data available for everyone to have a look and a play.

That will be very interesting.

[RayD]

1 minute ago, Allinthehead said:

That will be very interesting.

Yes I just thought same night(s), same target, same OTA, same filters (Baader) and same total integration time.  I don't think it would be possible to get a better comparison and I'll put all the .FITS files on Dropbox.  

I was going to start a thread to gauge interest as I will only dedicate the time if a few people would be keen on it, but I think it would be worthwhile.

[Allinthehead]

7 minutes ago, tooth_dr said:

The money you save on buying a CMOS is offset by the cost of buying a new high spec computer. 

Yes that is true. If you already have one however....

For me the biggest issue with the 1600 are the bright star reflections. Are there any low read noise ccd's that could be used with short subs circa 5 minutes as this is the advantage of cmos.

[Allinthehead]

6 minutes ago, RayD said:

Yes I just thought same night(s), same target, same OTA, same filters (Baader) and same total integration time

Yes unless it's done this way the comparison would be flawed. Your issue would be dithering i think as this is a must with the Horizon. 

You could time it around the longer subs of the ccd and just discard the dodgy Horizon subs.

[Laurin Dave]

1 minute ago, RayD said:

Yes I just thought same night(s), same target, same OTA, same filters (Baader) and same total integration time.  I don't think it would be possible to get a better comparison and I'll put all the .FITS files on Dropbox.  

I was going to start a thread to gauge interest as I will only dedicate the time if a few people would be keen on it, but I think it would be worthwhile.

I'd be very interested in a comparison Ray, your SX-814 I'd guess as very similar pixel size.  Maybe which is best could be target dependent i.e. galaxy or nebula

Dave

[tooth_dr]

9 minutes ago, Allinthehead said:

Are there any low read noise ccd's that could be used with short subs circa 5 minutes as this is the advantage of cmos.

Certainly not mine lol.  I like the idea of being able to use lots of shorter subs.  The other night I lost about 6 x 20 minute subs due to clouds and very briefly losing the guide star.  That is frustrating.

[RayD]

13 minutes ago, Laurin Dave said:

I'd be very interested in a comparison Ray, your SX-814 I'd guess as very similar pixel size.  Maybe which is best could be target dependent i.e. galaxy or nebula

Dave

Thanks, Dave.  That was the one I was thinking of. I also have a SX694, but that's just the same sensor as the 460, so probably not a great match.

I'd probably do one of each to make it a fair comparison, with one data set on a galaxy and one nebulae.

[Allinthehead]

1 minute ago, tooth_dr said:

The other night I lost about 6 x 20 minute subs due to clouds and very briefly losing the guide star.  That is frustrating.

That sounds painful. This is the beauty of the 150 second subs i use, you can be very critical of the subs you discard too. I think which route to take is very much dependent on your own particular needs and other equipment such as scope and mount. I mean the image i posted above could have been achieved using an EQ 3.  

[RayD]

1 minute ago, Allinthehead said:

That sounds painful. This is the beauty of the 150 second subs i use, you can be very critical of the subs you discard too. I think which route to take is very much dependent on your own particular needs and other equipment such as scope and mount. I mean the image i posted above could have been achieved using an EQ 3.  

That's actually a really good point.  I think if you have a very good mount and guide very well, the benefit reduces to effectively just cloud dodging.

I'm open minded and going to try it anyway, but certainly not with 30s subs, I'll probably be looking at around the 3 or 4 minute mark.

[RayD]

9 minutes ago, tooth_dr said:

Certainly not mine lol.  I like the idea of being able to use lots of shorter subs.  The other night I lost about 6 x 20 minute subs due to clouds and very briefly losing the guide star.  That is frustrating.

Yes I've had an instance taking 30 minute subs out in Spain during a new moon, pitch black and right at the end of a sub I stood up and smacked my head on the camera.......30 minutes wasted!!